1 files changed, 54 insertions, 0 deletions

diff --git a/lib/libc/gen/swapcontext.c b/lib/libc/gen/swapcontext.c
new file mode 100644
index 000000000000..5434c0f405fb
--- /dev/null
+++ b/lib/libc/gen/swapcontext.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2001 Daniel M. Eischen <deischen@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Neither the name of the author nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <errno.h>
+#include <signal.h>
+#include <ucontext.h>
+
+__weak_reference(__swapcontext, swapcontext);
+
+int
+__swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
+{
+	volatile int	swapped;
+	int		ret;
+
+	if (oucp == NULL || ucp == NULL) {
+		errno = EINVAL;
+		ret = -1;
+	}
+	else {
+		swapped = 0;
+		if ((ret = getcontext(oucp) == 0) && (swapped == 0)) {
+			swapped = 1;
+			ret = setcontext(ucp);
+		}
+	}
+	return (ret);
+}